Presentation on theme: "Principles of Physics. motion along a straight line path, motion in one dimension Which way are you headed? How far did you go? How fast are you."— Presentation transcript:
Principles of Physics
motion along a straight line path, motion in one dimension Which way are you headed? How far did you go? How fast are you going? Is your speed changing?
Direction In order to get anywhere you need to know what direction you are headed. North, South, West, East Up, Down, Left, Right Direction can also be negative or positive for math purposes Negative: South, West, Down, Left Positive: North, East, Up, Right
Almost all quantities have units - examples: meters, seconds, kilograms - Without units numbers would be meaningless Vector – Quantities that include a direction Vectors can be drawn They are represented by arrows Example: 12 m south Scalar – Quantities that do not include direction Example: 4 seconds
Path length (p): total length of path taken - measured in meters(m) - scalar quantity (does not include direction) How far did you go? 8 m 6 m 2 m 1 m p = 8 m + 6 m + 2 m + 1 m p = 17 m
Displacement (d): change in position, shortest path between start and finish - vector (amount and direction) - How far did you go? 8 m 6 m 2 m 1 m
6 m3 m Path Length = Displacement =9 m9 m right 6 m 3 m Path Length = Displacement =9 m3 m left 6 m 3 m Path Length = Displacement =9 m?
To determine displacement draw a diagram of the path taken Example: 8 m east, then 6m north, then 2 m east, then 1 m south Simplify the diagram to a right triangle Use Pythagorean Theorem to determine the displacement 8 m 6 m 2 m 1 m 8 m 6 m 2 m 1 m 10 m 5 m
Jan walks 4 meters north then turns to walk 4 meters east and finally turns to walk another 8 meters north. Determine Jan’s displacement. 4 m 8m 4 m 8m d
Units for path length or displacement: Standard Unit: meter Anything else must be converted 1 meter = 100 centimeters =.001 kilometer 1 kilometer = 1000 meters 1 meter = 3.28 feet 1 kilometer = miles
Smaller unit to larger unit: divide centimeters to meters: divide by 100 millimeters to meters: divide by 1000 Larger unit to smaller unit: multiply kilometers to meters: multiply by 1000
Smaller unit to larger unit: divide 1. Change 40 centimeters to meters Larger unit to smaller unit: multiply 2. Change 6.8 kilometers to meters